Hot rolling nickel silver alloy



United States Patent 3,372,026 HOT ROLLING NICKEL SILVER ALLOY RichardJ. Christine, Waterbury, Conn., assignor to Anaconda American BrassCompany, a corporation of Connecticut No Drawing. Filed Sept. 8, 1965,Ser. No. 485,954 4 Claims. (Cl. 75-1575) ABSTRACT OF THE DISCLOSURE Anickel silver alloy possessing improved hot working propertiesconsisting essentially of 730% Ni, 5-43% Zn, 0.003-0.3% Ti and thebalance Cu present in the range of 45-75%.

This invention relates to a nickel silver alloy which has improved hotworking properties, and more particularly, it relates to the addition offractional amounts of titanium to a nickel silver alloy to form a nickelsilver alloy that can be hot rolled.

It is widely accepted that the most economical way to reduce metal is byhot rolling because no strainhardening results and greater reductions inthickness can be obtained. In the case of nickel silvers, they generallyhave poor hot working properties and cannot be reduced by hot rollingwithout severe cracking of the rolled metal. Nickel silvers haveessentially two phases, a single-phase alpha nickel silver and atwo-phase alpha-beta nickel silver. The alpha-beta nickel silver can behot-worked but not with the results ordinarily achieved with brasses;the alpha nickel silvers have never been successfully hotworked withoutthe cracking problem mentioned above, and therefore they are used inapplications requiring ductility in the cold condition as they have goodcold working properties. Notwithstanding its cold working properties,the reduction of alpha nickels by cold rolling is an expensive processbecause they work-harden rapidly and require frequent anneals, and theyare prone to fire cracking during annealing which causes considerablemetal loss.

A similar problem with the single-phase alpha brasses was solved bykeeping the lead impurity below 0.015%. In nickel silvers, however, thepresence of zinc causes it to behave like the alpha brasses, ratherthan'like cupronickel and controlling the lead content has not solvedthe problem of cracking.

I have found that the addition of fractional amounts of titanium tonickel silvers greatly improves the hot working properties of the nickelsilver to the extent that a nickel silver alloy can be hot rolledwithout the appearance of cracks and it is possible to reduce therolling temperature to that at which brass is rolled, with an addedappreciable saving in heat requirements. Furthermore, although thestructural refinement which occurs has not fully been determined, theproperties of this new alloy are improved, particularly with respect tostresscorrosion cracking as indicated by the mercuric nitrate test;thus, the tendency to fire-crack during the one or two anneals requiredat the finishing stages is eliminated.

The nickel silver alloy of the invention is comprised of 45 to 75percent by weight Cu, 7 to 30 percent by weight Ni, 5 to 43 percent byweight Zn and 0.003 to 0.3 percent Ti. With alpha nickel silvers whichare comprised of 45 to percent by weight Cu, 7 to 25 percent by weightNi, 5 to 32 percent by weight Zn, it is preferred to include from about0.003 to 0.1 percent by weight Ti.

I It is to be noted that although the alpha-beta nickel sllvers can behot-worked somewhat without the addition of titanium, whereas hotworking was heretofore impossible with the alpha nickel silvers, thetitanium add1t1on to the alpha-beta nickel silvers is also beneficial.By alpha nickel silvers is meant a copper-nickel-zinc alloy containing45 to 75 percent by weight Cu, 7 to not more than about 25 percent byweight Ni, and 5 to not more than about 32 percent by weight Zn, which,under conditions of structural equilibrium comprise a single solidsolution, isomorphous with copper; above about 32 percent Zn, thealpha-beta nickel silver phase appears.

In one example four heats of nominal 18 percent alpha mckel silver (72percent by weight Cu, 18 percent by weight Ni, 9.74 percent by weightZn, 0.25 percent by weight Mn and 0.01 percent by weight Mg) weresemic-ontinuously cast into 3" x 17'' x 46" cakes. To the last two heatsa small titanium addition was made prior to pouring, specifically 0.036percent by weight Ti and 0.020 percent by weight respectively. All fourcakes were given a four hour soak at 900 C. Hot rolling temperatures asmeasured by a Land Radiation Pyrometer were 870 C. and 880 C. The cakeswithout the titanium addition cracked in hot rolling after two hotrolling passes of approximately 0.500" reduction per pass and werescrapped. The two cakes with the titanium addition were hot rolled to0.450" gauge without any cracking. Subsequent milling and cold rollingconfirmed the high quality of the nickel silver strip.

In another example, production semi-continuous castings 6%" x 26" x 72"of alpha nickel silvers were cast using titanium additions. Typicalanalyses in percent by weight are set out in the table below:

Heat B Heat 0 Heat D The cakes were soaked at 900 C. for four hoursprior to hot rolling. Hot rolling temperatures ranged from 860 C. to 900C. All cakes were hot rolled to 0.500 gauge in 15 passes withoutevidence of cracking or other hot rolling defects.

Advantages have been realized by titanium addition to all commercialimportant nickel silvers and it has been determined that generally theseadvantages are achieved by addition of titanium within a range of 0.003to 0.3 percent by weight, and with alpha nickel silvers a narrower rangeof .003 to 0.1 percent by weight Ti is preferred.

I claim:

1. A nickel silver alloy with improved hot working properties consistingessentially of 730% Ni, 543% 3 Zn, G.OO3O.3% Ti and the balanceessentially Cu, said Cu being present in the range of 4575%. e

2. A nickel silver alloy With improved hot Working properties consistingessentially of 7-30% Ni, 5-43% Zn, .O030.1% Ti and the balanceessentially Cu, said Cu being present in the range of 45-75%.

3. An alpha nickel silver alloy with improved hot working propertiesconsisting essentially of 725% Ni, 532% Zn, 0.003-0.3% Ti and thebalance essentially Cu, said Cu being present in the range of 45-75%.

4. An alpha nickel silver alloy With improved hot Working propertiesconsisting essentially of 725% Ni, 532% 4, p Zn, 0.003411% Ti and thebalance essentially Cu, said Cu being present in the range of 45-75%.

References Qited UNITED STATES PATENTS 2,035,423 3/1935 Bunn 75-157.52,752,242 6/1956 Holzwarth 75l59 FOREIGN PATENTS 553,142 2/1958 Canada.1,050,552 2/1959 Germany.

CHARLES N. LOVELL, Primary Examiner.

